Chapter 11: Physical and Cognitive Development in Adolescence

Anorexia Nervosa

+-.3Anorexia nervosais a tragic eating disorder in which young people starve themselves because of a compulsive fear of getting fat. About 1 percent of North American and Western European teenage girls are affected. During the past half-century, cases have increased sharply, fueled by cultural admiration of female thinness. In the United States, Asian-American, European-American, and Hispanic girls are at greater risk than African-American girls, whose greater satisfaction with their body image may offer some protection (American Psychiatric Association, 2013; Martin et al., 2015; Ozer & Irwin, 2009). Boys account for 10 to 15 percent of anorexia cases; up to half of these are gay or bisexual young people, who may be uncomfortable with a strong, bulky appearance or influenced by the cultural ideal of a lean but muscular male body (Darcy, 2012; Raevuori et al., 2009). Individuals with anorexia have an extremely distorted body image. Even after becoming severely underweight, they see themselves as too heavy. Most go on self-imposed diets so strict that they struggle to avoid eating in response to hunger. To enhance weight loss, they exercise strenuously. In their attempt to reach "perfect" slimness, individuals with anorexia lose 25 to 50 percent of their body weight. A normal menstrual cycle requires about 15 percent body fat, so many girls with anorexia experience delayed menarche or disrupted menstrual cycles. Malnutrition causes pale skin, brittle discolored nails, fine dark hairs all over the body, and extreme sensitivity to cold. If it continues, the heart muscle can shrink, the kidneys can fail, and irreversible brain damage and loss of bone mass can occur. About 5 percent of individuals with anorexia eventually die of the disorder. Forces within the person, the family, and the larger culture give rise to anorexia nervosa. Identical twins share the disorder more often than fraternal twins, indicating a genetic influence. Abnormalities in neurotransmitters in the brain, linked to anxiety and impulse control, may make some individuals more susceptible. Many young people with anorexia have unrealistically high standards for their own behavior and performance, are emotionally inhibited, and avoid intimate ties outside the family. Consequently, they are often excellent students who are responsible and well-behaved. But as we have also seen, the societal image of "thin is beautiful" contributes to the poor body image of many girls—especially early-maturing girls, who are at greatest risk. In addition, parent-adolescent interactions reveal problems related to adolescent autonomy. Often the mothers of these girls have high expectations for physical appearance, achievement, and social acceptance and are overprotective and controlling. Fathers tend to be either controlling or uninvolved. These parental attributes may contribute to affected girls' persistent anxiety and fierce pursuit of perfection in achievement, respectable behavior, and thinness. Nevertheless, it remains unclear whether maladaptive parent-child relationships precede the disorder, emerge as a response to it, or both. Because individuals with anorexia usually deny or minimize the seriousness of their disorder, treatment is difficult. Hospitalization is often necessary to prevent life-threatening malnutrition. The most successful treatment is family therapy and medication to reduce anxiety and neurotransmitter imbalances. Still, less than 50 percent of young people with anorexia recover fully.

Propositional Thought

A second important characteristic of Piaget's formal operational stage is propositional thought—adolescents' ability to evaluate the logic of propositions (verbal statements) without referring to real-world circumstances. In contrast, children can evaluate the logic of statements only by considering them against concrete evidence in the real world. In a study of propositional reasoning, a researcher showed children and adolescents a pile of poker chips and asked whether statements about the chips were true, false, or uncertain. Although Piaget did not view language as playing a central role in children's cognitive development (see Chapter 7), he acknowledged its importance in adolescence. Formal operations require language-based and other symbolic systems that do not stand for real things, such as those in higher mathematics. Secondary school students use such systems in algebra and geometry. Formal operational thought also involves verbal reasoning about abstract concepts. Jules was thinking in this way when he pondered relationships among time, space, and matter in physics and wondered about justice and freedom in philosophy.

Muscle-fat makeup

Around age 8, girls start to add fat on their arms, legs, and trunk, a trend that accelerates between ages 11 and 16. In contrast, arm and leg fat decreases in adolescent boys. Although both sexes gain in muscle, this increase is much greater in boys, who develop larger skeletal muscles, hearts, and lung capacity (Rogol, Roemmich, & Clark, 2002). Also, the number of red blood cells—and therefore the ability to carry oxygen from the lungs to the muscles—increases in boys but not in girls. Altogether, boys gain far more muscle strength than girls, a difference that contributes to boys' superior athletic performance during the teenage years

Pubertal timing

Both adults and peers viewed early-maturing boys as relaxed, independent, self-confident, and physically attractive. Popular with agemates, they tended to hold leadership positions in school and to be athletic stars. Late-maturing boys often experienced transient emotional difficulties, until they caught up physically with their peers. But early-maturing boys, though viewed as well-adjusted, reported more psychological stress, depressed mood, and problem behaviors (sexual activity, smoking, drinking, aggression, delinquency) than both their on-time and later-maturing agemates. In contrast, early-maturing girls were unpopular, withdrawn, lacking in self-confidence, anxious, and prone to depression, and they held few leadership positions. And like early-maturing boys, they were more involved in deviant behavior. In contrast, their later-maturing counterparts were regarded as physically attractive, lively, sociable, and leaders at school. Two factors largely account for these trends: (1) how closely the adolescent's body matches cultural ideals of physical attractiveness, and (2) how well young people fit in physically with their peers.

hormonal changes in boys during puberty

Boys' maturing testes release large quantities of the androgen testosterone, which leads to muscle growth, body and facial hair, and other male sex characteristics. Androgens (especially testosterone) exert a GH-enhancing effect, contributing to gains in body size. The testes secrete small amounts of estrogen as well. In both sexes, estrogens in combination with androgens stimulate gains in bone density, which continue into early adulthood

Pubertal Development in North American Girls

Breasts begin to bud: 8-13 (10) Height spurt begins: 8-13 (10) Pubic hair appears: 8-14 (10.5) Peak strength spurt: 9.5-14 (11.6) Peak height spurt: 10-13.5 (11.7) Menarche (first menstruation occurs): 10.5-15.5 (12.5) Peak weight spurt: 10-14 (12.7) Adult stature reached: 10-16 (13) Pubic hair growth completed: 14-15 (14.5) Breast growth completed: 10-17 (15)

Sexual orientation in adolescence

About 5 percent of U.S. high school students identify as lesbian, gay, or bisexual, and another 2 to 3 percent report being unsure of their sexual orientation. An unknown number experience same-sex attraction but have not come out to friends or family. Heredity makes an important contribution to sexual orientation: Identical twins of both sexes are more likely than fraternal twins to share a homosexual orientation; so are biological (as opposed to adoptive) relatives. Furthermore, male homosexuality tends to be more common on the maternal than on the paternal side of families, suggesting that it may be X-linked. How might heredity influence sexual orientation? According to some researchers, certain genes affect the level or impact of prenatal sex hormones, which modify brain structures in ways that induce homosexual feelings and behavior. Keep in mind, however, that environmental factors can also alter prenatal hormones. Girls exposed prenatally to very high levels of androgens or estrogens—either because of a genetic defect or from drugs given to the mother to prevent miscarriage—are more likely to develop lesbian or bisexual orientations. Furthermore, gay men tend to be later in birth order and to have a higher-than-average number of older brothers. Perhaps mothers with several male children sometimes produce antibodies to androgens, reducing the prenatal impact of male sex hormones on the brains of later-born boys. Stereotypes and misconceptions about homosexuality and bisexuality persist. For example, contrary to common belief, most sexual minority adolescents and adults are not "gender-deviant" in dress or behavior. And attraction to members of the same sex is not limited to lesbian, gay, and bisexual teenagers. In recent surveys, between 17 and 78 percent of teenagers who reported sexual experiences with same-sex partners identified as heterosexual. And a study of lesbian, bisexual, and "unlabeled" young women confirmed that bisexuality is not, as often assumed, a transient state. Over a 10-year period, most reported stable proportions of same-sex versus other-sex attractions over time. The evidence to date indicates that genetic and prenatal biological influences contribute substantially to homosexuality. The origins of bisexuality are not yet known.

Adolescent pregnancy and parenthood

About 625,000 U.S. teenage girls (almost 11,000 of them younger than age 15)—an estimated 13 percent of those who had sexual intercourse—became pregnant in the most recently reported year. Despite a decline of more than 50 percent since 1990, the U.S. adolescent pregnancy rate remains higher than that of most other industrialized countries. Because about one-fourth of U.S. adolescent pregnancies end in abortion, the number of teenage births is considerably lower than it was 50 years ago. Still, the United States greatly exceeds most other developed nations in adolescent birth rate. And teenage parenthood remains a problem today because contemporary adolescents rarely marry before childbirth. In 1960, only 15 percent of teenage births were to unmarried females, compared with 89 percent today. Increased social acceptance of single motherhood, along with the belief of many teenage girls that a baby might fill a void in their lives, means that very few girls give up their infants for adoption.

Sexual Maturation

Accompanying rapid body growth are changes in physical features related to sexual functioning. Some, called primary sexual characteristics, involve the reproductive organs (ovaries, uterus, and vagina in females; penis, scrotum, and testes in males). Others, called secondary sexual characteristics, are visible on the outside of the body and serve as additional signs of sexual maturity (for example, breast development in females and the appearance of underarm and pubic hair in both sexes). These characteristics develop in a fairly standard sequence, although the ages at which each begins and is completed vary greatly. Typically, pubertal development takes about 4 years, but some adolescents complete it in 2 years, whereas others take 5 to 6 years.

Piaget's Formal Operational Stage

According to Piaget, around age 11 young people enter the formal operational stage, in which they develop the capacity for abstract, systematic, scientific thinking. Whereas concrete operational children can "operate on reality," formal operational adolescents can "operate on operations." They no longer require concrete things or events as objects of thought. Instead, they can come up with new, more general logical rules through internal reflection

Academic achievement

Adolescent achievement is the result of a long history of cumulative effects. Early on, positive educational environments, both family and school, lead to personal traits that support achievement—intelligence, confidence in one's own abilities, the desire to succeed, and high educational aspirations. Nevertheless, improving an unfavorable environment can foster resilience among poorly performing young people.

Self Conscious and Self Focusing

Adolescents' ability to reflect on their own thoughts, combined with physical and psychological changes, leads them to think more about themselves. Piaget's followers identified two distorted images of the relation between self and other that commonly appear. The first is called the imaginary audience, adolescents' belief that they are the focus of everyone else's attention and concern (Elkind & Bowen, 1979). As a result, they become extremely self-conscious. The imaginary audience helps explain why adolescents spend long hours inspecting every detail of their appearance and why they are so sensitive to public criticism. To teenagers, who believe that everyone is monitoring their performance, a critical remark from a parent or teacher can be mortifying. A second cognitive distortion is the personal fable. Certain that others are observing and thinking about them, teenagers develop an inflated opinion of their own importance—a feeling that they are special and unique. Many adolescents view themselves as reaching great heights of omnipotence and also sinking to unusual depths of despair—experiences that others cannot possibly understand. Imaginary-audience and personal-fable ideation is partly an outgrowth of hormonal changes that heighten social sensitivity (see page 302) and of advances in perspective taking, which cause young teenagers to be more concerned with what others think (Albert, Chein, & Steinberg, 2013; Vartanian & Powlishta, 1996). When asked why they worry about the views of others, adolescents respond that others' evaluations have important real consequences—for self-esteem, peer acceptance, and social support (Bell & Bromnick, 2003). With respect to the personal fable, in a study of sixth through tenth graders, sense of omnipotence predicted self-esteem and overall positive adjustment. Viewing the self as highly capable and influential helps young people cope with challenges of adolescence. In contrast, sense of personal uniqueness was associated with depression and suicidal thinking (Aalsma, Lapsley, & Flannery, 2006). Focusing on the distinctiveness of one's own experiences may interfere with forming close, rewarding relationships, which provide social support in stressful times.

Idealism and Criticism

Adolescents' capacity to think about possibilities opens up the world of the ideal. Teenagers can imagine alternative family, religious, political, and moral systems, and they want to explore them. They often construct grand visions of a world with no injustice, discrimination, or tasteless behavior. The disparity between teenagers' idealism and adults' greater realism creates tension between parent and child. Envisioning a perfect family against which their parents and siblings fall short, adolescents become fault-finding critics. Overall, however, teenage idealism and criticism are advantageous. Once adolescents come to see other people as having both strengths and weaknesses, they have a much greater capacity to work constructively for social change and to form positive, lasting relationships

hormonal changes in girls during puberty

Adrenal androgens influence girls' height spurt, and they stimulate growth of underarm and pubic hair. (Adrenal androgens have little visible impact on boys, whose physical characteristics are mainly influenced by androgen secretions from the testes.) Estrogens released by girls' maturing ovaries contribute to the height spurt by stimulating GH secretion, and they cause the breasts, uterus, and vagina to mature, the body to take on feminine proportions, and fat to accumulate. In addition, estrogens play a crucial role in regulating the menstrual cycle.

Contraceptive use in adolescence

Although adolescent contraceptive use has increased in recent years, about 14 percent of sexually active teenagers in the United States are at risk for unintended pregnancy because they do not use contraception consistently. Why do so many fail to take precautions? We have seen that in the midst of everyday peer pressures and heightened emotion, self-regulation is difficult for teenagers, who often overlook the potential consequences of risky behaviors. They are least likely to use condoms in relatively new relationships in which they feel high trust or love and are having sex often. Adolescents who report good relationships with parents and who talk openly with them about sex and contraception are more likely to use birth control. But few teenagers believe their parents would be understanding and supportive. School sex education classes, as well, often leave teenagers with incomplete or incorrect knowledge. Some do not know where to get birth control counseling and devices or how to discuss contraception with a partner. And those engaged in high-risk sexual behaviors are especially likely to worry that a doctor or family planning clinic might not keep their visits confidential. Most of these young people forgo essential health care but continue to have sex without contraception.

athletic competence in adolescence

Among boys, athletic competence is strongly related to peer admiration and self-esteem. Some adolescents become so obsessed with physical prowess that they turn to performance-enhancing drugs. More than 9 percent of U.S. high school seniors, mostly boys, report having used creatine, an over-the-counter substance that enhances short-term muscle power but is associated with serious side effects, including muscle tissue disease, brain seizures, and heart irregularities. About 2 percent of seniors, again mostly boys, have taken anabolic steroids or a related substance, androstenedione—powerful prescription medications that boost muscle mass and strength. Teenagers usually obtain steroids illegally, ignoring side effects, which range from acne, excess body hair, and high blood pressure to mood swings, aggressive behavior, and damage to the liver, circulatory system, and reproductive organs. Coaches and health professionals should inform teenagers of the dangers of these performance-enhancing substances.

Prevention Strategies

Among the diverse strategies available for helping teenagers at risk of dropping out, several common themes are related to success: Supplementary academic instruction and counseling that offer personalized attention. Most potential dropouts need intensive remedial instruction in small classes that permit warm, caring teacher-student relationships to form (Wilson & Tanner-Smith, 2013). In one successful approach, at-risk students are matched with retired adults, who serve as tutors, mentors, and role models in addressing academic and vocational needs (Prevatt, 2003). High-quality vocational education. For many marginal students, the real-life nature of vocational education is more comfortable and effective than purely academic work (Levin, 2012). To work well, vocational education must carefully integrate academic and job-related instruction so students see the relevance of classroom experiences to their future goals. Efforts to address the many factors in students' lives related to leaving school early. Programs that strengthen parent involvement, offer flexible work-study arrangements, and provide on-site child care for teenage parents can make staying in school easier for at-risk adolescents. Participation in arts, community service, or vocational development activities promotes improved academic performance, reduced antisocial behavior, more favorable self-esteem and initiative, and increased peer acceptance (Fredricks, 2012; Fredricks & Eccles, 2006). Participation in extracurricular activities. Another way of helping marginal students is to draw them into the community life of the school. The most powerful influence on extracurricular involvement is small school size (Feldman & Matjasko, 2007). As high school student body declines—dropping from 2,000 students to 500 to 700 students— at-risk youths are more likely to be needed to help staff activities. As a result, they feel more attached to their school. Creation of smaller "schools within schools" has the same effect. As we conclude our discussion of academic achievement, let's place the school dropout problem in historical perspective. Over the second half of the twentieth century, the percentage of U.S. young people completing high school by age 24 increased steadily, from less than 50 percent to more than 90 percent. Although many dropouts get caught in a vicious cycle in which their lack of self-confidence and skills prevents them from seeking further education and training, of the 25 percent of high school freshmen who do not graduate on time, more than two-thirds return to finish their secondary education by their mid-twenties (U.S. Department of Education, 2015). And some extend their schooling further as they come to realize how essential education is for a rewarding job and a satisfying adult life.

Race and pubertal growth

But in industrialized nations where food is abundant, the joint roles of heredity and environment in pubertal growth are apparent. For example, African-American girls reach menarche about six months earlier than their European-American agemates (Ramnitz & Lodish, 2013). Although widespread overweight and obesity in the black population contribute, a genetically influenced faster rate of physical maturation is also involved. Black girls usually reach menarche before white girls of the same age and body weight

Classroom learning experiences

As noted earlier, in large, departmentalized secondary schools, many adolescents report that their classes lack warmth and supportiveness, which dampens their motivation. Of course, an important benefit of separate classes in each subject is that adolescents can be taught by experts, who are more likely to encourage high-level thinking and emphasize content relevant to students' experiences—factors that contribute to interest, effort, and achievement. But many classrooms do not consistently provide stimulating, challenging teaching. Wide variability in quality of instruction has contributed to increasing numbers of seniors who graduate from high school deficient in basic academic skills. Although the achievement gap separating African-American, Hispanic, and Native-American students from white students has declined since the 1970s, mastery of reading, writing, mathematics, and science by low-SES ethnic minority students remains disappointing (U.S. Department of Education, 2012a, 2012b, 2016). Too often these young people attend underfunded schools with rundown buildings, outdated equipment, and textbook shortages. In some, crime and discipline problems receive more attention than teaching and learning. By middle school, many low-SES minority students have been placed in low academic tracks, compounding their learning difficulties. Once assigned to a low track, students are "locked out" of advanced courses in later grades because they have not taken prerequisite courses, which restricts them to a lower-quality curriculum (Kelly & Price, 2011). Compared to students in higher tracks, those in low tracks decline in academic self-esteem and exert substantially less effort—differences due in part to less stimulating classroom experiences and reduced teacher expectations (Chiu et al., 2008; Worthy, Hungerford-Kresser, & Hampton, 2009). High school students are separated into academic and vocational tracks in virtually all industrialized nations. In China, Japan, and most Western European countries, students' placement is determined by a national exam, which usually establishes the young person's future possibilities. In the United States, students who are not assigned to a college preparatory track or who do poorly in high school can still attend college. Ultimately, however, many young people do not benefit from the more open U.S. system. By adolescence, SES differences in quality of education and academic achievement are greater in the United States than in most other industrialized countries. And the United States has a higher percentage of young people who see themselves as educational failures and drop out of high school.

Helping adolescents adjust to school transitions

As these findings reveal, school transitions often lead to environmental changes that fit poorly with adolescents' developmental needs. They disrupt close relationships with teachers at a time when adolescents need adult support. They emphasize competition during a period of heightened self-focusing. They reduce decision making and choice as the desire for autonomy is increasing. And they interfere with peer networks as young people become more concerned with peer acceptance. Support from parents, teachers, and peers can ease these strains (Waters, Lester, & Cross, 2014). Parental involvement, monitoring, gradual autonomy granting, and emphasis on mastery rather than merely good grades are associated with better adjustment (Gutman, 2006). Adolescents with close friends are more likely to sustain these friendships across the transition, which increases social integration and academic motivation in the new school (Aikens, Bierman, & Parker, 2005). Some school districts reduce the number of school transitions by combining elementary and middle school into K-8 buildings. Compared with agemates who transition to middle school, K-8 sixth and seventh graders score higher in achievement (Kleffer, 2013; Schwerdt & West, 2013). Furthermore, teachers and administrators in K-8 buildings report more positive social contexts—less chaos, fewer conduct problems, and better overall working conditions (Kim et al., 2014). These factors predict students' favorable school attitudes, academically and socially. Other less extensive changes are also effective. Forming smaller units within larger schools promotes closer relationships with both teachers and peers along with greater extracurricular involvement (Seidman, Aber, & French, 2004). And a "critical mass" of same-ethnicity peers—according to one suggestion, at least 15 percent of the student body—helps teenagers feel socially accepted and reduces fear of out-group hostility (National Research Council, 2007). In the first year after a school transition, homerooms can be provided in which teachers offer academic and personal counseling. Assigning students to classes with several familiar peers or a constant group of new peers strengthens emotional security and social support. In schools that take these steps, students are less likely to decline in academic performance or display other adjustment problems

2 types of pubertal changes

As you can see, pubertal changes are of two broad types: (1) overall body growth and (2) maturation of sexual characteristics. Boys and girls differ in both aspects. In fact, puberty is the time of greatest sexual differentiation since prenatal life.

Child-rearing styles

Authoritative parenting is linked to higher grades and achievement test scores among adolescents varying widely in SES, just as it predicts mastery-oriented behavior in childhood (Collins & Steinberg, 2006; Pinquart, 2016). In contrast, authoritarian, permissive, and uninvolved styles are associated with poorer achievement and declines in academic performance over time. In Chapter 8, we noted that authoritative parents adjust their expectations to children's capacity to take responsibility for their own behavior. Warmth, open discussion, firmness, and monitoring of adolescents' whereabouts and activities make young people feel cared about and valued and encourage reflective thinking and self-regulation. These factors, in turn, are related to mastery-oriented attributions, effort, achievement, and high educational aspirations

The importance of fitting in with peers in adolescence

Because early-maturing adolescents of both sexes feel physically "out of place" when with their agemates, they often seek out older companions, who may encourage them into activities they are not yet ready to handle. And pubertal hormonal influences on the brain's emotional/social network are stronger for early maturers, further magnifying their receptiveness to sexual activity, drug and alcohol use, and delinquent acts. Perhaps as a result, early maturers of both sexes more often report feeling emotionally stressed and decline in academic performance. At the same time, the young person's context greatly increases the likelihood that early pubertal timing will lead to negative outcomes. Early maturers in economically disadvantaged neighborhoods are especially vulnerable to establishing ties with deviant peers. And because families in such neighborhoods tend to be exposed to chronic, severe stressors and to have few social supports, these early maturers are also more likely to experience harsh, inconsistent parenting, which, in turn, predicts deviant peer associations as well as antisocial behavior and depressive symptoms.

Sports and cognitive and social development

Besides improving motor performance, sports and exercise influence cognitive and social development, providing lessons in teamwork, problem solving, assertiveness, and competition. And regular, sustained physical activity—which required physical education can ensure—is associated with lasting physical and mental health benefits and enjoyment of sports and exercise

Binge-Eating Disorder

Between 2 and 3 percent of adolescent girls and close to 1 percent of boys experience episodes of binge-eating disorder—binging at least once a week for three months or longer, without compensatory purging, exercise, or fasting. Binge-eating disorder, like bulimia, is unrelated to ethnicity. It typically leads to overweight and obesity, but binge eaters do not engage in the prolonged, restrictive dieting characteristic of anorexia and bulimia. As with other eating disorders, binge-eating disorder is associated with social adjustment difficulties, and many binge eaters—similar to individuals with bulimia—experience severe emotional distress and suicidal thoughts. Effective treatments resemble those used for bulimia.

Heredity and pubertal growth

Heredity contributes substantially to the timing of pubertal changes. Identical twins are more similar than fraternal twins in attainment of most pubertal milestones

Emotional turbulence in adolescence

Contemporary research shows that the storm-and-stress notion of adolescence is exaggerated. Certain problems, such as eating disorders, depression, suicide, and lawbreaking, do occur more often than earlier. But the overall rate of serious psychological disturbance rises only slightly from childhood to adolescence, reaching 15 to 20 percent. Though much greater than the adulthood rate (about 6 percent), emotional turbulence is not a routine feature of the teenage years.

Coming Out

Cultures vary widely in their acceptance of sexual minorities. In the United States, societal attitudes toward lesbian, gay, and bisexual people have become more accepting, but prejudice remains widespread. This makes forming a sexual identity more challenging for sexual minority youths than for their heterosexual counterparts. Wide variation in sexual identity formation exists, depending on personal, family, and community factors. Yet interviews with lesbian and gay adolescents and adults reveal that many move through a three-phase sequence in coming out to themselves and others. Feeling Different Typically, the first sense of a biologically determined lesbian or gay sexual orientation appears between ages 6 and 12, in play interests more like those of the other gender. Boys may find that they are less interested in sports, more drawn to quieter activities, and more emotionally sensitive than other boys; girls that they are more athletic and active than other girls. By age 10, many of these children start to engage in sexual questioning—wondering why the typical heterosexual orientation does not apply to them. Confusion With the arrival of puberty, feeling different clearly encompasses feeling sexually different. On average, boys begin to think they are gay at around age 10 and know for sure at around age 15. Awareness tends to emerge a few years later for girls, around 13 and 18, respectively, perhaps because social pressures toward heterosexuality are particularly intense for adolescent girls. Realizing that same-sex attraction has personal relevance generally sparks additional confusion. A few adolescents resolve their discomfort by crystallizing a lesbian, gay, or bisexual identity quickly, with a flash of insight into their sense of being different. But most experience an inner struggle that is intensified by lack of role models and social support. Some throw themselves into activities they associate with heterosexuality. Boys may go out for athletic teams; girls may drop softball and basketball in favor of dance. And many lesbian and gay youths (more females than males) try heterosexual dating. Those who are extremely troubled and guilt-ridden may escape into alcohol, drugs, and suicidal thinking. Suicide attempts are unusually high among lesbian, gay, and bisexual young people. Self-Acceptance By the end of adolescence, the majority of lesbian, gay, and bisexual teenagers accept their sexual identity. But they face another crossroad: whether to tell others. Stigma against their sexual orientation leads some to decide that disclosure is impossible. When they do come out, sexual minority youths often face peer hostility, including verbal abuse and physical attacks. These experiences trigger intense emotional distress, depression, school truancy, and drug use in victims. Nevertheless, many young people eventually acknowledge their sexual orientation publicly, usually by telling trusted friends first. Once teenagers establish a same-sex sexual or romantic relationship, many come out to parents. Few parents respond with severe rejection; most are either positive or slightly negative and disbelieving. Still, lesbian, gay, and bisexual young people report lower levels of family support than their heterosexual agemates. Parental understanding is a key predictor of favorable adjustment—including reduced internalized homophobia, or societal prejudice turned against the self. When people react positively, coming out strengthens the young person's sexual identity as valid, meaningful, and fulfilling. Contact with lesbian, gay, and bisexual peers is important for reaching this phase, and changes in society permit many adolescents in urban areas to attain it earlier than their counterparts did a decade or two ago. Gay and lesbian communities exist in large cities, along with specialized interest groups, social clubs, religious groups, newspapers, and periodicals. But teenagers in small towns and rural areas may have difficulty finding a supportive environment. These adolescents have a special need for caring adults and peers who can help them find self- and social acceptance. Lesbian, gay, and bisexual teenagers who succeed in coming out to themselves and others integrate their sexual orientation into a broader sense of identity. As a result, energy is freed for other aspects of psychological growth. In sum, coming out can foster many facets of adolescent development, including self-esteem, psychological well-being, and relationships with family and friends.

Impact of culture on sexuality

Despite the prevailing image of sexually free adolescents, sexual attitudes in North America are relatively restrictive. Typically, parents provide little or no information about sex, discourage sex play, and rarely talk about sex in children's presence. When young people become interested in sex, only about half report getting information from parents about intercourse, pregnancy prevention, and sexually transmitted infections. Many parents avoid meaningful discussions about sex out of fear of embarrassment or concern that the adolescent will not take them seriously. Yet warm, open give-and-take is associated with teenagers' adoption of parents' views, discussions about sexual health with dating partners, and reduced sexual risk taking. Adolescents who do not get information about sex from their parents are likely to learn from friends, siblings, books, magazines, movies, TV, and the Internet. Among TV shows that adolescents prefer, more than 80 percent contain sexual content. Most depict partners as spontaneous and passionate, taking no steps to avoid pregnancy or sexually transmitted infections, and experiencing no negative consequences. Teenagers' exposure to sexualized media predicts increased sexual activity, pregnancy, and sexual harassment behaviors (offensive name-calling or touching, pressuring a peer for a date), even after many other relevant factors are controlled. Adolescents who are prone to engage in early sex choose to consume more sexualized media. Still, the Internet is a hazardous "sex educator." In a survey of a large sample of U.S. 10- to 17-year-old Web users, 42 percent said they had viewed online pornographic websites (images of naked people or people having sex) while surfing the Internet in the past 12 months. Of these, 66 percent indicated they had encountered the images accidentally and did not want to view them. Youths who felt depressed, had been bullied by peers, or were involved in delinquent activities had more encounters with Internet pornography, which may have intensified their adjustment problems. Consider the contradictory messages young people receive. On one hand, adults express disapproval of sex at a young age. On the other hand, the social environment extols sexual excitement, experimentation, and promiscuity. American teenagers are left bewildered, poorly informed about sexual facts, and with little sound advice on how to conduct their sex lives responsibly.

Body growth trends

During puberty, the cephalocaudal growth trend of infancy and childhood reverses. The hands, legs, and feet accelerate first, followed by the torso, which accounts for most of the adolescent height gain. This pattern helps explain why early adolescents often appear awkward and out of proportion—long-legged, with giant feet and hands.

Early family experiences and pubertal growth

Early family experiences may also affect pubertal timing. One theory suggests that humans have evolved to be sensitive to the emotional quality of their childhood environments. When children's safety and security are at risk, it is adaptive for them to reproduce early. Research indicates that girls and (less consistently) boys with a history of family conflict, harsh parenting, parental separation, or single mothers tend to reach puberty early. In contrast, those with warm, stable family ties reach puberty relatively late. For girls, two longitudinal studies confirm this chain of influence from adverse childhood family environments to earlier pubertal timing to increased adolescent sexual risk taking

Factors related to dropping out

Many dropouts show a persistent pattern of disruptive behavior combined with poor academic performance (Hawkins, Jaccard, & Needle, 2013). But others, like Norman, have few behavior problems; they simply experience academic difficulties and quietly disengage from school (Balfanz, Herzog, & MacIver, 2007). The pathway to dropping out starts early. Risk factors in first grade predict dropout nearly as well as risk factors in secondary school (Entwisle, Alexander, & Olson, 2005). Norman—like other dropouts—had a long history of marginal-to-failing school grades and low academic self-esteem (Wexler & Pyle, 2013). As Norman got older, he attended class less regularly, paid little attention when he was there, and rarely did his homework. He didn't join school clubs or participate in sports. As a result, few teachers or students got to know him well. By the day he left, Norman felt alienated from all aspects of school life. As with other dropouts, Norman's family background contributed to his problems. Compared with other students, even those with the same grade profile, dropouts are more likely to have parents who are uninvolved in their teenager's education and engage in little monitoring of their youngster's daily activities. Many are single parents, never finished high school themselves, and are unemployed (Pagani et al., 2008; Song, Benin, & Glick, 2012). Students who drop out often have school experiences that undermine their chances for success: grade retention, which marks them as academic failures; classes with unsupportive teachers and few opportunities for active participation; and frequent peer victimization (Brown & Rodriguez, 2009; Peguero, 2011). Students in general education and vocational tracks are three times as likely to drop out as those in a college preparatory track (U.S. Department of Education, 2015). Boys' higher rates of learning and behavior problems from early childhood on contribute to their greater school leaving relative to girls.

Nutrition and exercise and pubertal growth

Nutrition and exercise also make a difference. In females, a sharp rise in body weight and fat may hasten sexual maturation. Fat cells release a protein called leptin, which is believed to signal the brain that the girl's energy stores are sufficient for puberty—a likely reason that breast and pubic hair growth and menarche occur earlier for heavier and, especially, obese girls. In contrast, girls who begin rigorous athletic training at an early age or who eat very little (both of which reduce the percentage of body fat) usually experience later puberty. Few studies, however, report a link between body fat and puberty in boys.

Reactions to menarche

Girls commonly react to menarche with "surprise," undoubtedly due to the sudden onset of the event. Otherwise, they typically report a mixture of positive and negative emotions. Yet wide individual differences exist that depend on prior knowledge and support from family members. For girls who have no advance information, menarche can be shocking and disturbing. And cultural or religious views of menstruation as unclean, embarrassing, or a source of weakness requiring restriction of activities also promote distressed reaction. Unlike 50 to 60 years ago, today few girls in developed countries are uninformed, a shift that is probably due to parents' greater willingness to discuss sexual matters and to the spread of health education classes. Almost all girls get some information from their mothers. And some evidence suggests that compared with European-American families, African-American families may treat menarche as an important milestone and express less conflict over girls reaching sexual maturity—factors that lead African-American girls to react more favorably.

Sexual maturation in girls

Female puberty usually begins with the budding of the breasts and the growth spurt. Menarche, or first menstruation, typically occurs around age 12½ for North American girls, 13 for Western Europeans. But the age range is wide, from 10½ to 15½ years. Following menarche, breast and pubic hair growth are completed, and underarm hair appears. Nature delays sexual maturity until the girl's body is large enough for childbearing; menarche takes place after the peak of the height spurt. As an extra measure of security, for 12 to 18 months following menarche, the menstrual cycle often occurs without the release of an ovum from the ovaries. But this temporary period of sterility does not occur in all girls, and it does not provide reliable protection against pregnancy.

Long term consequences of early maturers

Follow-up research reveals that early-maturing girls, especially, are at risk for lasting difficulties. In one study, depression and frequently changing sexual partners persisted into early adulthood among early-maturing girls, with depression evident mainly in those who had displayed the severest adolescent conduct problems. In another study, which followed young people from ages 14 to 24, early-maturing girls reported poorer-quality relationships with family and friends, smaller social networks, and lower life satisfaction in early adulthood than did their on-time counterparts. Recall that childhood family conflict and harsh parenting are linked to earlier pubertal timing, more so for girls than for boys. Perhaps many early-maturing girls enter adolescence with emotional and social difficulties. As the stresses of puberty interfere with school performance and lead to unfavorable peer pressures, poor adjustment may extend and deepen. Clearly, interventions that target at-risk early-maturing youths are needed. These include educating parents and teachers and providing adolescents with counseling and social supports.

Eating disorders in adolescence

Girls who reach puberty early and who grow up in homes where concern with weight and thinness is high are at risk for eating problems. Body dissatisfaction and severe dieting are strong predictors of an eating disorder in adolescence. Disturbed eating is highest in Western nations, but with the spread of Western media and cultural values, Africa, Asia, and the Middle East are increasingly affected. The three most serious eating disorders are anorexia nervosa, bulimia nervosa, and binge-eating disorder.

Adolescent moodiness

Higher pubertal hormone levels are linked to greater moodiness, but only modestly so. What other factors might contribute? In several studies, the moods of children, adolescents, and adults were monitored by having them carry electronic pagers that beeped at random intervals, signaling them to write down what they were doing, whom they were with, and how they felt. As expected, adolescents' moods were the least favorable. But negative moods were linked to a greater number of negative life events, such as conflicts with parents, disciplinary actions at school, and breaking up with a boyfriend or girlfriend. Furthermore, compared with the moods of older adolescents and adults, those of younger adolescents (ages 12 to 16) were less stable and strongly related to situational changes. Low points tended to occur in adult-structured settings—class, job, and religious services. High points were times spent with peers and coincided with Friday and Saturday evenings, especially in high school. Going out with friends and romantic partners increases so dramatically during adolescence that it becomes a "cultural script" for what is supposed to happen. Consequently, teenagers who spend weekend evenings at home often feel profoundly lonely. Fortunately, frequent reports of negative mood level off in late adolescence.

Media Multitasking disrupts learning

In a survey of a nationally representative sample of U.S. 8- to 18-year-olds, more than two-thirds reported engaging in two or more media activities at once, some or most of the time (Rideout, Foehr, & Roberts, 2010). When observed studying in their homes for just 15 minutes, adolescents diverted, on average, every 5 to 6 minutes to texting, social media sites, phone calling, or watching TV (Rosen, Carrier, & Cheever, 2013). The presence of a television in the young person's bedroom is a strong predictor of this behavior, as is access to a mobile device—especially a smartphone. Nearly three-fourths of U.S. teenagers have smartphones, and one-fourth report being online "almost constantly". Research confirms that media multitasking greatly reduces learning. In one experiment, participants were given two tasks: learning to predict the weather in two different cities using colored shapes as cues and keeping a mental tally of how many high-pitched beeps they heard through headphones. Half the sample performed the tasks simultaneously, the other half separately (Foerde, Knowlton, & Poldrack, 2006). Both groups learned to predict the weather in the two-city situation, but the multitaskers were unable to apply their learning to new weather problems. fMRI evidence revealed that the participants working only on the weather task activated the hippocampus, which plays a vital role in explicit memory—conscious, strategic recall, which enables new information to be used flexibly and adaptively in contexts outside the original learning situation (see page 190 in Chapter 7). In contrast, the multitaskers activated subcortical areas involved in implicit memory—a shallower, automatic form of learning that takes place unconsciously. Adolescents who often media multitask report problems with each aspect of executive function in everyday life—working memory ("I forget what I'm doing in the middle of things"), inhibition ("It's hard for me to wait my turn"), and flexibly shifting attention ("I have trouble changing from one activity to another") (Baumgartner et al., 2014). Consequently, beyond superficial preparation for her biology test, Ashley is likely to have difficulty concentrating and strategically processing new information after turning off her electronic devices. Experienced teachers often complain that compared to students of a generation ago, today's teenagers are more easily distracted and learn less thoroughly. One teacher reflected, "It's the way they've grown up—working short times on many different things at one time"

Bulimia Nervosa

In bulimia nervosa, young people (again, mainly girls, but gay and bisexual boys are also vulnerable) engage in binge eating, followed by compensatory efforts to avoid weight gain, such as deliberate vomiting, purging with laxatives, excessive exercise, or fasting. Bulimia typically appears in late adolescence and is more common than anorexia nervosa, affecting about 2 to 4 percent of teenage girls, only 5 percent of whom previously suffered from anorexia. Bulimia is not consistently linked to ethnicity. Twin studies show that bulimia, like anorexia, is influenced by heredity. Overweight and early menarche increase the risk. Some adolescents with bulimia, like those with anorexia, are perfectionists. But most are impulsive, sensation-seeking young people who are especially prone to act irrationally when distressed and who engage in petty shoplifting, alcohol abuse, and other risky behaviors. And although girls with bulimia, like those with anorexia, are pathologically anxious about gaining weight, they may have experienced their parents as disengaged and emotionally unavailable rather than as controlling. In contrast to young people with anorexia, those with bulimia usually feel depressed and guilty about their abnormal eating habits, and many report suicidal thoughts. Because affected individuals desperately want help, bulimia is usually easier to treat than anorexia, through support groups, nutrition education, training in changing eating habits, and anti-anxiety, antidepressant, and appetite-control medication.

Learning in school

In complex societies, adolescence coincides with entry into secondary school. Most young people move into either a middle or a junior high school and then into a high school. With each change, academic achievement increasingly determines higher education options and job opportunities. In the following sections, we take up various aspects of secondary school life.

Poverty and pubertal growth

In poverty-stricken regions where malnutrition and infectious disease are common, menarche is greatly delayed, occurring as late as age 14 in parts of Africa and Asia. Within developing countries, girls from higher-income families reach menarche 6 to 18 months earlier than those living in economically disadvantaged homes

Parent-school partnerships

In response to teenagers' desire for greater autonomy, parents' volunteering at school and contact with teachers tend to decline over adolescence. Nevertheless, high-achieving students typically have parents who remain invested in their teenager's education (Hill & Taylor, 2004). They keep tabs on academic progress, regularly attend parent-teacher conferences, make sure the young person is enrolled in challenging, well-taught classes, and emphasize the importance of doing well in school and engaging in academic planning. In a large sample of U.S. tenth graders, students whose parents encouraged educational pursuits and high achievement more often completed homework on time, less often skipped class, and expressed greater interest and enjoyment in school learning (Wang & Sheikh-Khalil, 2014). When followed up nearly two years later, they gained in grade point average relative to agemates with less involved parents, beyond the influence of SES and previous academic performance. Academically involved parents send a message to their youth about the value of education, model constructive solutions to academic problems, and promote wise educational decisions. Compared to parents in neighborhoods with ample resources, parents in depleted, high-risk neighborhoods tend to report higher levels of academic involvement with their teenagers at home. They seem to work harder at conveying to their children the value of education, even though daily stressors reduce their energy for such involvement (Bhargava & Witherspoon, 2015; Bunting et al., 2013). Yet stronger home-school links can relieve some of this stress. Schools can build parent-school partnerships by strengthening relationships between teachers and parents, organizing communities of parents who mutually support one another, and including parents in school governance so they remain aware of and invested in school goals.

storm and stress perspective

In the early twentieth century, major theorists viewed adolescence from a "storm-and-stress" perspective. The most influential, G. Stanley Hall (1904), who based his ideas on Darwin's theory of evolution, described adolescence as a period so turbulent that it resembled the era in which humans evolved from savages into civilized beings. Similarly, Anna Freud (1969), who expanded the focus on adolescence of her father Sigmund Freud's theory, viewed the teenage years as a biologically based "developmental disturbance."

Secular trends in pubertal growth

In the research we have considered, threats to emotional health accelerate puberty, whereas threats to physical health delay it. A secular trend, or generational change, in pubertal timing lends added support to the role of physical well-being in pubertal development. In industrialized nations, age of menarche declined steadily—by about 3 to 4 months per decade—from 1900 to 1970, a period in which nutrition, health care, sanitation, and control of infectious disease improved greatly. Boys, too, have reached puberty earlier in recent decades. And as developing nations make socioeconomic progress, they also show secular gains. In most industrialized nations, the trend toward earlier menarche has stopped or undergone a slight reversal. But in the United States and a few European countries, soaring rates of overweight and obesity are responsible for a modest, continuing trend toward earlier menarche. A worrisome consequence is that girls who reach sexual maturity at age 10 or 11 will experience pressure for unfavorable peer involvements, including sexual activity.

An Information-Processing View of Adolescent Cognitive Development

Information-processing theorists refer to a variety of specific mechanisms, including components of executive function, as underlying cognitive gains in adolescence. Each was discussed in previous chapters (Keating, 2012; Kuhn, 2009, 2013). Now let's draw them together: 1. Working memory increases, enabling more information to be held in mind at once and combined into increasingly complex, efficient representations, "opening possibilities for growth" in the capacities listed below and also improving as a result of gains in those capacities (Demetriou et al., 2002, p. 97). 2. Inhibition—both of irrelevant stimuli and of well-learned responses in situations where they are inappropriate—improves, supporting gains in attention and reasoning. 3. Attention becomes more selective (focused on relevant information) and flexible—better-adapted to the changing demands of tasks. 4. Planning on complex tasks with multiple steps improves, becoming better-organized and efficient. 5. Strategies become more effective, enhancing storage, representation, and retrieval of information. 6. Knowledge increases, easing strategy use. 7. Metacognition (awareness of thought) expands, leading to new insights into effective strategies for acquiring information and solving problems. 8. Cognitive self-regulation improves, yielding better moment-by-moment monitoring, evaluation, and redirection of thinking. As we look at influential findings from an information-processing perspective, we will see some of these changes in action. And we will discover that researchers regard one of them—metacognition—as central to adolescent cognitive development.

Bodily sex differences in puberty

Large sex differences in body proportions also appear, caused by the action of sex hormones on the skeleton. Boys' shoulders broaden relative to the hips, whereas girls' hips broaden relative to the shoulders and waist. Of course, boys also end up larger than girls, and their legs are longer in relation to the rest of the body—mainly because boys have two extra years of preadolescent growth, when the legs are growing the fastest.

Correlates of adolescent parenthood

Life conditions and personal attributes jointly contribute to adolescent childbearing. Teenage parents are far more likely to come from poverty-stricken homes than agemates who postpone parenthood. Their backgrounds often include low parental warmth and involvement, domestic violence, child abuse and neglect, repeated parental divorce and remarriage, adult models of unmarried parenthood, and residence in neighborhoods where other adolescents also display these risks. Girls at risk for early pregnancy do poorly in school, use drugs and alcohol, have a childhood history of aggressive and antisocial behavior, associate with deviant peers, and experience high rates of depression. Many turn to early parenthood as a pathway to adulthood when educational and career avenues are unavailable.

Boy's reaction to spermarche

Like girls' reactions to menarche, boys' responses to spermarche reflect mixed feelings. Virtually all boys know about ejaculation ahead of time, but many say that no one spoke to them before or during puberty about physical changes. Usually they get their information from reading material or websites. Whereas almost all girls eventually tell a friend that they are menstruating, far fewer boys tell anyone about spermarche. Overall, boys get less social support than girls for the changes of puberty.

Initiation ceremonies

Many tribal and village societies celebrate the onset of puberty with an initiation ceremony, a ritualized announcement to the community that marks an important change in privilege and responsibility. Consequently, young people know that reaching puberty is a significant milestone in their culture. In contrast, Western societies grant little formal recognition to movement from childhood to adolescence or from adolescence to adulthood. Ceremonies such as the Jewish bar or bat mitzvah and the quinceañera in Hispanic communities (celebrating a 15-year-old girl's sexual maturity and marriage availability) resemble initiation ceremonies, but only within the ethnic or religious subculture. They do not mark a significant change in social status in the larger society. Instead, Western adolescents are granted partial adult status at many different ages—for example, an age for starting employment, for driving, for leaving high school, for voting, and for drinking. The absence of a widely accepted marker of physical and social maturity makes the process of becoming an adult more confusing.

Dropping out

One of about 7 percent of U.S. 16- to 24-year-olds who dropped out of high school and remain without a diploma or a GED (U.S. Department of Education, 2015). The overall dropout rate has declined since the mid-2000s, largely due to substantial gains in Hispanic teenagers' graduation rates. Nevertheless, as Figure 11.7 shows, dropout rates remain elevated among low-SES ethnic minority youths, especially Native-American and Hispanic teenagers. Also, boys drop out at considerably higher rates than girls. The decision to leave school has dire consequences. Youths without upper secondary education have much lower literacy scores than high school graduates, and they lack the skills valued by employers in today's knowledge-based economy. Consequently, dropouts have much lower employment rates than high school graduates. Even when employed, dropouts are far more likely to remain in menial, low-paid jobs.

Characteristics of Adolescents Who Engage in Early Sexual Activity

Overall, teenage sexual activity rates are similar in the United States and other Western countries: Nearly half of adolescents have had intercourse. But quality of sexual experiences differs. U.S. youths become sexually active earlier—a substantial minority by ages 15 to 16. About 70 percent of sexually active teenagers report that they first had sex with a steady dating partner, and most have only one or two partners during high school. But 12 percent of high school students report having sexual relations with four or more partners. Mutually consensual sexual activity in the context of a stable, caring romantic relationship can be a positive and satisfying experience for older adolescents. But when teenagers engage in casual sex, or have sex when they have been drinking or using drugs, they often report negative feelings, including guilt and depression. A variety of adverse personal, family, peer, and educational characteristics are linked to early and frequent teenage sexual activity. These include childhood impulsivity, weak sense of personal control over life events, early pubertal timing, parental divorce, single-parent and stepfamily homes, large family size, little or no religious involvement, weak parental monitoring, disrupted parent-child communication, sexually active friends and older siblings, poor school performance, lower educational aspirations, and tendency to engage in norm-violating acts, including alcohol and drug use and delinquency. Many of these factors are associated with growing up in economically disadvantaged homes. Living in a neighborhood high in physical deterioration, crime, and violence also increases the likelihood that teenagers will be sexually active. In such neighborhoods, social ties are weak, adults exert little oversight and control over adolescents' activities, negative peer influences are widespread, and teenagers are unlikely to consider the impact of early parenthood on their current and future lives. In fact, the high rate of early sexual activity among African-American teenagers—8 percent report having had sexual intercourse before age 13, compared with 4 percent of all U.S. young people—may be largely explained by widespread poverty in the black population.

Peer influences

Peers play an important role in adolescent achievement, in a way that relates to both family and school. Teenagers whose parents value achievement generally choose friends who share those values. Peer support for high achievement also depends on the overall climate of the peer culture, which, for ethnic minority youths, is powerfully affected by the surrounding social order. In one study, integration into the school peer network predicted higher grades among European-American and Hispanic students but not among Asians and African Americans (Faircloth & Hamm, 2005). Asian cultural values stress respect for family and teacher expectations over close peer ties. African-American minority adolescents may observe that their ethnic group is worse off than the white majority in educational attainment, jobs, income, and housing. And discriminatory treatment by teachers and peers, often resulting from stereotypes that they are "not intelligent," triggers anger, anxiety, self-doubt, declines in motivation and achievement, association with peers who are not interested in school, and increases in problem behaviors (Wong, Eccles, & Sameroff, 2003). Schools that build close networks of support between teachers and peers can prevent these negative outcomes. One high school with a largely low-income ethnic minority student body (65 percent African American) reorganized into "career academies"—learning communities within the school, each offering a different career-related curriculum (for example, one focusing on health, medicine, and life sciences, another on computer technology). The vocationally relevant academic program combined with more caring teacher-student relationships helped create a school climate in which peers valued school engagement (Conchas, 2006). High school graduation and college enrollment rates rose from a small minority to over 90 percent. Finally, teenagers' use of text messaging, e-mail, and social media sites to remain continuously in touch with peers—even during class and while working on homework—is an aspect of contemporary peer-group life that poses risks to achievement.

Hypothetico-Deductive Reasoning

Piaget believed that at adolescence, young people first become capable of hypothetico-deductive reasoning. When faced with a problem, they start with a hypothesis, or prediction about variables that might affect an outcome, from which they deduce logical, testable inferences. Then they systematically isolate and combine variables to see which of these inferences are confirmed in the real world. Notice how this form of problem solving begins with possibility and proceeds to reality. In contrast, concrete operational children start with reality—with the most obvious predictions about a situation. If these are not confirmed, they usually cannot think of alternatives and fail to solve the problem. Adolescents' performance on Piaget's famous pendulum problem illustrates this approach. Suppose we present several school-age children and adolescents with strings of different lengths, objects of different weights to attach to the strings, and a bar from which to hang the strings (see Figure 11.5). Then we ask each of them to figure out what influences the speed with which a pendulum swings through its arc. Formal operational adolescents hypothesize that four variables might be influential: (1) the length of the string, (2) the weight of the object hung on it, (3) how high the object is raised before it is released, and (4) how forcefully the object is pushed. By varying one factor at a time while holding the other three constant, they test each variable separately and, if necessary, also in combination. Eventually they discover that only string length makes a difference. In contrast, concrete operational children cannot separate the effects of each variable. They may test for the effect of string length without holding weight constant—comparing, for example, a short, light pendulum with a long, heavy one. Also, they typically fail to notice variables that are not immediately suggested by the concrete materials of the task—for example, how high the object is raised or how forcefully it is released.

Teen pregnancy prevention strategies

Preventing teenage pregnancy means addressing the many factors underlying early sexual activity and lack of contraceptive use. Sex education courses typically improve awareness of sexual facts—knowledge necessary for responsible sexual behavior. Knowledge, however, is not enough: Sex education must also help teenagers build a bridge between what they know and what they do. Effective sex education programs include several key elements: 1. They teach techniques for handling sexual situations—including communication skills for avoiding risky sexual behaviors—through role-playing and other activities. 2. They deliver clear, accurate messages that are appropriate in view of participating adolescents' culture and sexual experiences. 3. They last long enough to have an impact. 4. They provide specific information about contraceptives and ready access to them. Many studies show that sex education with these components can delay the initiation of sexual activity, increase contraceptive use, and reduce pregnancy rates. Proposals to increase access to contraceptives are the most controversial aspect of U.S. adolescent pregnancy prevention efforts. Yet sex education programs promoting abstinence without also advocating contraceptive use have little or no impact on delaying teenage sexual activity or preventing pregnancy. In Canada and Western Europe, where community- and school-based clinics offer adolescents contraceptives and where universal health insurance helps pay for them, teenage sexual activity is no higher than in the United States—but pregnancy, childbirth, and abortion rates are much lower. Efforts to prevent adolescent pregnancy and parenthood must go beyond improving sex education and access to contraception to build academic and social competence. In a program called Teen Outreach, at-risk adolescents participated in a year-long community service class in which they spent at least 20 hours per week in volunteer work tailored to their interests, returning to school for discussions that focused on enhancing their sense of connection to the community, ability to cope with everyday challenges, social skills, and self-respect. Compared to controls in regular classes, adolescents randomly assigned to Teen Outreach displayed substantially lower end-of-year rates of pregnancy, school failure, and school suspension. Finally, teenagers who look forward to a promising future are far less likely to engage in early and irresponsible sex. By expanding educational, vocational, and employment opportunities, society can give young people good reasons to postpone childbearing.

Motor development in adolescence

Puberty brings steady improvements in gross motor performance, but the pattern of change differs for boys and girls. Girls' gains are slow and gradual, leveling off by age 14. In contrast, boys show a dramatic spurt in strength, speed, and endurance that continues through the teenage years. By midadolescence, few girls perform as well as the average boy in running speed, broad jump, or throwing distance

Nutritional needs in adolescence

Puberty leads to a dramatic increase in nutritional requirements, at a time when the diets of many young people are the poorest. Of all age groups, adolescents are the most likely to skip breakfast (a practice linked to overweight and obesity), eat on the run, and consume empty calories. Fast-food restaurants, where teenagers often gather, have begun to offer some healthy menu options, and many schools now offer more nutritious choices (French & Story, 2013). But adolescents need guidance in selecting these alternatives. Sweets, soft drinks, pizza, and French fries still figure prominently in the diets of young people, especially those from low-SES families. Frequency of family meals is strongly associated with healthy eating in teenagers. But compared to families with younger children, those with adolescents eat fewer meals together.

Parent-child relationships in adolescence

Research shows that puberty is related to a rise in intensity of parent-child conflict, and to fluctuations between positive and negative parent-child interaction, that persists into midadolescence. Why should young teenagers' more adultlike appearance trigger these disputes? The association may have adaptive value. Among nonhuman primates, the young typically leave the family group around the time of puberty. The same is true in many village and tribal cultures. Departure of young people discourages sexual relations between close blood relatives. But adolescents in industrialized nations, who are still economically dependent on parents, cannot leave the family. Consequently, a substitute seems to have emerged: psychological distancing. As children become physically mature, they demand to be treated in adultlike ways. And as we will see, adolescents' new powers of reasoning may also contribute to a rise in family tensions. Parent-adolescent disagreements focus largely on everyday matters such as driving, dating partners, and curfews. But beneath these disputes lie serious concerns: parental efforts to protect teenagers from substance use, auto accidents, and early sexual activity. Parent-daughter conflict tends to be more intense than conflict with sons, perhaps because parents place more restrictions on girls. But most disputes are mild, and by late adolescence, only a small minority of families experience continuing friction. Throughout adolescence, positive parent-child problem solving greatly exceeds angry confrontations.

Prevention and Treatment of Drug abuse in adolescence

School and community programs that reduce drug experimentation typically combine several components. These include promoting effective parenting, emphasizing health and safety risks of drug taking, and teaching skills for resisting peer pressure. One intervention, the Strong African American Families (SAAF) program, teaches parents to monitor their adolescents' behavior, communicate and enforce clear expectations, and use cooperative problem solving to resolve disputes. Evaluations revealed that SAAF reduced substance use among African-American youths, and it was most effective for adolescents with the DRD4 7-repeat or the short 5-HTTLPR gene (see pages 154 and 160 in Chapter 6), which placed them at risk for self-regulation difficulties (Brody et al., 2009, 2014). Does this remind you of evidence discussed in previous chapters indicating that good parenting can protect the development of genetically vulnerable children? Programs that teach at-risk teenagers effective strategies for handling life stressors and that build competence through community service reduce alcohol and drug use, just as they reduce teenage pregnancy. Providing appealing substitute activities is also helpful. Physical activity works especially well as a substitute for cigarette smoking. In a program aimed at helping teenagers stop smoking, participants were most likely to cut back or quit when the intervention also helped them exercise more (Horn et al., 2013). When an adolescent becomes a drug abuser, family and individual therapy are generally needed to treat maladaptive parent-child relationships, impulsivity, low self-esteem, anxiety, and depression. Academic and vocational training to improve life success also helps. But even comprehensive programs have alarmingly high relapse rates—from 35 to 85 percent (Brown & Ramo, 2005; Sussman, Skara, & Ames, 2008). Adolescents who are motivated at the start of treatment have better outcomes (Joe et al., 2014). One recommendation is to initiate treatment gradually, through support-group sessions that focus on reducing drug taking. Modest improvements may boost the young person's sense of self-efficacy for behavior change and, as a result, increase motivation to make longer-lasting changes through intensive treatment.

Are Children Capable of Hypothetico-Deductive and Propositional Thinking?

School-age children show the glimmerings of hypothetico-deductive reasoning, although they are less competent at it than adolescents. In simplified situations involving no more than two possible causal variables, 6-year-olds understand that hypotheses must be confirmed by appropriate evidence (Ruffman et al., 1993). But without direct instruction, school-age children cannot sort out evidence that bears on three or more variables at once (Lorch et al., 2010; Matlen & Klahr, 2013). And children have difficulty explaining why a pattern of observations supports a hypothesis, even when they recognize the connection between the two. With respect to propositional thought, when a simple set of premises defies real-world knowledge ("All cats bark. Rex is a cat. Does Rex bark?") but is presented with the support of props in make-believe play, 4- to 6-year-olds can reason logically. To justify their answer, they are likely to say, "We can pretend cats bark!" (Dias & Harris, 1988, 1990). But in an entirely verbal mode, children have great difficulty reasoning from premises that contradict reality or their own beliefs. Consider this set of statements: "If dogs are bigger than elephants and elephants are bigger than mice, then dogs are bigger than mice." Children younger than 10 judge this reasoning to be false because some of the relations specified do not occur in real life (Moshman & Franks, 1986; Pillow, 2002). They automatically think of well-learned knowledge ("Elephants are larger than dogs") that casts doubt on the truthfulness of the premises. Children find it more difficult than adolescents to inhibit activation of such knowledge (Klaczynski, Schuneman, & Daniel, 2004; Simoneau & Markovits, 2003). Partly for this reason, they fail to grasp the logical necessity of propositional reasoning—that the accuracy of conclusions drawn from premises rests on the rules of logic, not on real-world confirmation. As with hypothetico-deductive reasoning, in early adolescence, young people become better at analyzing the logic of propositions, regardless of their content. And they handle problems requiring increasingly complex mental operations. In justifying their reasoning, they more often explain the logical rules on which it is based (Müller, Overton, & Reese, 2001; Venet & Markovits, 2001). But these capacities do not appear suddenly at puberty. Rather, gains are gradual from childhood on—findings that call into question the emergence of a new stage of cognitive development at adolescence (Kuhn, 2009; Moshman, 2005).

Handling Consequences of teenagers' new cognitive capacities

Sensitivity to public criticismAvoid finding fault with the adolescent in front of others. If the matter is important, wait until you can speak to the teenager alone.Exaggerated sense of personal uniquenessAcknowledge the adolescent's unique characteristics. At opportune times, encourage a more balanced perspective by pointing out that you had similar feelings as a teenager.Idealism and criticismRespond patiently to the adolescent's grand expectations and critical remarks. Point out positive features of targets, helping the teenager see that all societies and people are blends of virtues and imperfections.Difficulty making everyday decisionsRefrain from deciding for the adolescent. Model effective decision making, and offer diplomatic suggestions about the pros and cons of alternatives, the likelihood of various outcomes, and learning from poor choices.

Sexually Transmitted Infections

Sexually active adolescents, regardless of sexual orientation, are at risk for sexually transmitted infections (STIs). Young people from 15 to 24 have the highest rates of STIs of all age groups. In recent years, U.S. rates have risen: 1 out of 5 sexually active teenagers contracts an STI each year—a rate three or more times that of Canada and Western Europe. Left untreated, STIs can lead to sterility and life-threatening complications. By far the most serious STI is HIV/AIDS. In contrast to other Western nations, where the incidence of HIV infection among people under age 30 is low, one-fourth of U.S. HIV cases are young people between ages 13 and 24. Because AIDS symptoms typically do not emerge until 8 to 10 years after HIV infection, many young adults diagnosed with HIV or AIDS contracted the virus during adolescence. Males who have sex with HIV-positive same-sex partners account for most of these cases. But one-fourth are due to heterosexual spread of the disease, mostly through male-to-female transmission. It is at least twice as easy for a male to infect a female with any STI, including HIV, as for a female to infect a male. As a result of school courses and media campaigns, most adolescents are aware of basic facts about HIV and AIDS. But they have limited understanding of other STIs and are poorly informed about how to protect themselves. Furthermore, high school students report engaging in oral sex much more often than intercourse, and with more partners. But few consistently use STI protection during oral sex, which is a significant mode of transmission for several STIs. Concerted efforts are needed to educate young people about the full range of STIs and risky sexual behaviors.

Substance Use and Abuse in adolescence

Teenage alcohol and drug use is pervasive in industrialized nations. According to the most recent nationally representative survey of U.S. high school students, 20 percent of tenth graders have tried smoking, 47 percent drinking, and 37 percent at least one illegal drug (usually marijuana). Among twelfth graders, 6 percent smoke cigarettes regularly, 17 percent have engaged in heavy drinking during the past month, and 21 percent have used marijuana. About 21 percent have tried at least one highly addictive and toxic substance, such as amphetamines, cocaine, phencyclidine (PCP), Ecstasy (MDMA), inhalants, heroin, sedatives (including barbiturates), or OxyContin (a narcotic painkiller) (Johnston et al., 2015). These figures represent a substantial decline since the mid-1990s, probably resulting from greater parent, school, and media focus on the hazards of drug taking. An exception is use of marijuana, which began to rise in the mid-2000s but has recently leveled off. Many states have passed medical use laws and a few have legalized recreational use, making it easier for young people to obtain marijuana (Johnston et al., 2015). In part, drug taking reflects the sensation seeking of the teenage years. But adolescents also live in drug-dependent cultural contexts. They see adults relying on caffeine to stay alert, alcohol and cigarettes to cope with daily hassles, and other remedies to relieve stress, depression, and physical discomfort. They also encounter high rates of cigarette, alcohol, and drug use in TV programs, movies, and advertisements (Strasburger, 2012). And compared to a decade or two ago, today doctors more often prescribe—and parents frequently seek—medication to treat children's problems (Olfman & Robbins, 2012). In adolescence, these young people may readily "self-medicate" when stressed. Most teenagers who try alcohol, tobacco, or marijuana are not headed for a life of addiction. These occasional experimenters are usually psychologically healthy, sociable, curious young people. Nevertheless, adolescent experimentation with any drug should not be taken lightly. Because most drugs impair perception and thought processes, a single heavy dose can lead to permanent injury or death. And a worrisome minority of teenagers move from substance use to abuse—taking drugs regularly, requiring increasing amounts to achieve the same effect, moving on to harder substances, and using enough to interfere with their ability to meet daily responsibilities.

Pubertal Development in North American Boys

Testes begin to enlarge: 9.5-13.5 (11.5) Pubic hair appears: 10-15 (12) Penis begins to enlarge: 10.5-14.5 (12) Height spurt begins: 10.5-16 (12.5) Spermarche (first ejaculation) occurs: 12-16 (13.5) Peak height spurt: 12.5-15.5 (14) Facial hair begins to grow: 12.5-15.5 (14) Voice begins to deepen: 12.5-16 (14) Penis and testes growth completed: 12.5-16 (14.5) Peak strength spurt: 13-17 (15.3) Adult stature reached: 13.5-17.5 (15.5) Pubic hair growth completed: 14-17 (15.5)

puberty

The beginning of adolescence is marked by puberty, a flood of biological events leading to an adult-sized body and sexual maturity. As Sabrina's reactions suggest, entry into adolescence can be an especially trying time for some young people. The changes of puberty are dramatic. Within a few years, the school-age child's body transforms into that of a full-grown adult. Genetically influenced hormonal processes regulate pubertal growth. Girls, who have been advanced in physical maturity since the prenatal period, reach puberty, on average, two years earlier than boys.

Hormonal Changes in puberty

The complex hormonal changes that underlie puberty occur gradually and are under way in middle childhood. Secretions of growth hormone (GH) and thyroxine increase, eventually leading to tremendous gains in body size and to attainment of skeletal maturity. Sexual maturation is controlled by the sex hormones. Although we think of estrogens as female hormones and androgens as male hormones, both types are present in each sex but in different amounts. Sex hormones begin to rise long before physical changes are visible, typically between ages 6 and 8, when the adrenal glands on top of each kidney start to release increasing levels of adrenal androgens. By age 10, levels of adrenal androgens have increased tenfold, and some children experience their first feelings of sexual attraction.

Sexual maturation in boys

The first sign of puberty in boys is the enlargement of the testes (glands that manufacture sperm), accompanied by changes in the texture and color of the scrotum. Pubic hair emerges soon after, about the same time the penis begins to enlarge. The growth spurt occurs much later in the sequence of pubertal events for boys than for girls. When it reaches its peak around age 14, enlargement of the testes and penis is nearly complete, and underarm hair appears. So do facial and body hair, which increase gradually for several years. Another landmark of male physical maturity is the deepening of the voice as the larynx enlarges and the vocal cords lengthen. (Girls' voices also deepen slightly.) While the penis is growing, the prostate gland and seminal vesicles (which together produce semen, the fluid containing sperm) enlarge. Then, around age 13½, spermarche, or first ejaculation, occurs. For a while, the semen contains few living sperm. So, like girls, boys have an initial period of reduced fertility.

Consequences of adolescent cognitive changes

The development of increasingly complex, effective thinking leads to dramatic revisions in the way adolescents see themselves, others, and the world in general. But just as adolescents are occasionally awkward in using their transformed bodies, so they initially falter in their abstract thinking. Teenagers' self-concern, idealism, criticism, and faulty decision making, though perplexing to adults, are usually beneficial in the long run.

Growth spurt

The first outward sign of puberty is the rapid gain in height and weight known as the growth spurt. On average, it is under way for North American and Western European girls shortly after age 10, for boys around age 12½. Because estrogens trigger and then restrain GH secretion more readily than androgens, the typical girl is taller and heavier during early adolescence. By age 13½, she is surpassed by the typical boy, whose adolescent growth spurt has now started, whereas hers is almost finished. Growth in body size is complete for most girls by age 16 and for boys by age 17½, when the epiphyses at the ends of the long bones close completely. Altogether, adolescents add 10 to 11 inches in height and 50 to 75 pounds—nearly 50 percent of adult body weight.

Margaret Mead

The first researcher to point out the wide variability in adolescent adjustment was anthropologist Margaret Mead. Returning from the Pacific islands of Samoa, she concluded that because of the culture's relaxed social relationships and openness toward sexuality, adolescence "is perhaps the pleasantest time the Samoan girl (or boy) will ever know". In Mead's alternative view, the social environment is entirely responsible for the range of teenage experiences, from erratic and agitated to calm and stress-free. Later researchers, however, found that Samoan adolescence was not as untroubled as Mead had assumed

Scientific Reasoning: Coordinating Theory with Evidence

The heart of scientific reasoning is coordinating theories with evidence. Researchers have conducted extensive research into the development of scientific reasoning, using problems that, like Piaget's tasks, involve several variables that, alone or in combination, might affect an outcome (Lehrer & Schauble, 2015). In one series of studies, third, sixth, and ninth graders and adults were first presented with evidence—sometimes consistent and sometimes conflicting with theories—and then questioned about the accuracy of each theory (Kuhn, 2002). For example, participants were given a problem much like Sabrina's: to theorize about which of several features of sports balls—size (large or small), color (light or dark), texture (rough or smooth), or presence or absence of ridges on the surface—influences the quality of a player's serve. Next, they were told about the theory of Mr. (or Ms.) S, who believes the ball's size is important, and the theory of Mr. (or Ms.) C, who thinks color matters. Finally, the interviewer presented evidence by placing balls with certain characteristics in two baskets, labeled "good serve" and "bad serve" The youngest participants often discounted obviously causal variables, ignored evidence conflicting with their own initial judgment, and distorted evidence in ways consistent with their preferred theory. These findings, and others like them, suggest that on complex, multivariable tasks, children—instead of viewing evidence as separate from and bearing on a theory—often blend the two into a single representation of "the way things are." Children are especially likely to overlook evidence that does not match their prior beliefs when a causal variable is implausible (like color affecting the performance of a sports ball) and when task demands (number of variables to be evaluated) are high (Yang & Tsai, 2010). The ability to distinguish theory from evidence and use logical rules to examine their relationship improves steadily from childhood into adolescence, continuing into adulthood

Consequences of adolescent parenthood

The lives of expectant teenagers, already troubled in many ways, tend to worsen in several respects after the baby is born. Adolescent mothers are less likely than their peers to finish high school, get married, or secure employment. About 35 percent become pregnant again within two years; of these, about half go on to deliver a second child. Teenage mothers who do marry are more likely to divorce and, consequently, spend more of their child-rearing years as single parents. Because of low educational attainment, marital instability, and poverty, many teenage mothers are on welfare or work in unsatisfying, low-paid jobs. Adolescent fathers, too, are generally unemployed or earn too little to provide their children with basic necessities. And for both mothers and fathers, reduced educational and occupational attainment often persists well into adulthood. Because many pregnant teenage girls do not receive early prenatal care, their babies often experience pregnancy and birth complications—especially low birth weight. And compared with adult mothers, adolescent mothers know less about child development, perceive their babies as more difficult, interact less effectively with them, and more often engage in harsh or abusive parenting. Their children typically score low on intelligence tests, achieve poorly in school, and engage in disruptive social behavior. Furthermore, because adolescent parenthood is linked to a set of unfavorable family conditions and personal characteristics that negatively affect development over an extended time, it often transfers to the next generation. Even when children born to teenage mothers do not become early childbearers, their development is often compromised. Many drop out of school, struggle financially, and experience long-term physical and mental health difficulties. The circumstances that lead to adolescent parenthood are likely responsible for many of the negative consequences associated with it. Still, outcomes vary widely. If a teenage parent finishes high school, secures gainful employment, avoids additional births, and finds a stable partner, long-term disruptions in her own and her child's development will be less severe.

Intervening with Adolescent Parents

The most difficult and costly way to deal with adolescent parenthood is to wait until it happens. Young parents need health care, encouragement to stay in school, job training, instruction in parenting and life-management skills, and high-quality, affordable child care. Schools that provide these services reduce the incidence of low-birth-weight babies, increase educational success, and prevent additional childbearing. Adolescent mothers also benefit from relationships with family members and other adults who are sensitive to their developmental needs. Those with more social support report reduced levels of depression during the year after giving birth. In one study, African-American teenage mothers who had a long-term "mentor" relationship—an aunt, neighbor, or teacher who provided emotional support and guidance—were far more likely than those without a mentor to stay in school and graduate. Home visiting programs are also effective. Return to page 73 in Chapter 3 to review the Nurse-Family Partnership, which helps launch teenage mothers and their babies on a favorable life course. Although half of young fathers visit their children during the first few years, contact usually diminishes over time. As with teenage mothers, support from family members helps fathers stay involved. Mothers who receive financial and child-care assistance and emotional support from their child's father are less distressed and more likely to sustain a relationship with him. And children with lasting ties to their teenage fathers show better long-term adjustment

Brain development in adolescence

The physical transformations of adolescence include major changes in the brain. Brain-imaging research reveals continued pruning of unused synapses in the cerebral cortex, especially the prefrontal cortex. Growth and myelination of stimulated neural fibers accelerate, further strengthening connections among various brain regions. In particular, linkages between the prefrontal cortex and other areas in the cerebral cortex and the inner brain (including the amygdala and hippocampus) expand and attain rapid communication. Consequently, adolescents gain in diverse cognitive skills, including executive function, reasoning, problem solving, and decision making. But these advances in cognitive control occur gradually over the teenage years. fMRI evidence reveals that adolescents recruit the prefrontal cortex's network of connections with other brain areas less effectively than adults do. Because the prefrontal cognitive-control network still requires fine-tuning, teenagers' performance on tasks requiring inhibition, planning, and delay of gratification (rejecting a smaller immediate reward in favor of a larger, later reward) is not yet fully mature. Adding to these executive function and self-regulation difficulties are changes in the brain's emotional/social network. As humans and other mammals become sexually mature, neurons become more responsive to excitatory neurotransmitters. As a result, adolescents react more strongly to stressful events and experience pleasurable stimuli more intensely. Changes in the emotional/social network also increase adolescents' sensitivity to social stimuli, making them highly reactive to peer influence and evaluation. Because the cognitive-control network is not yet functioning optimally, most teenagers find it especially difficult to manage these powerful feelings and impulses. This imbalance contributes to teenagers' unchecked drive for novel experiences, including drug taking, reckless driving, unprotected sex, and delinquent activity. In a longitudinal study of a large, representative sample of U.S. youths, researchers tracked changes in self-reported impulsivity and sensation seeking between ages 12 and 24. As Figure 11.2 shows, impulsivity declined steadily with age—evidence of gradual improvement of the cognitive-control network. But sensation seeking increased from 12 to 16, followed by a more gradual decline through age 24, reflecting the challenge posed by the emotional/social network. In sum, changes in the adolescent brain's emotional/social network outpace development of the cognitive-control network. Only over time are young people able to effectively manage their emotions and reward-seeking behavior. Of course, wide individual differences exist in the extent to which teenagers manifest this rise in risk taking in the form of careless, dangerous acts. Temperament, parenting, SES, and neighborhood resources, which are linked to willingness, encouragement, and opportunities to take risks, make a difference. At puberty, revisions also occur in brain regulation of sleep, perhaps because of increased neural sensitivity to evening light. As a result, adolescents go to bed much later than they did as children. Yet they need almost as much sleep as they did in middle childhood—about nine hours. When the school day begins early, their sleep needs are not satisfied. This sleep "phase delay" strengthens with pubertal growth. But today's teenagers—with more evening social activities, part-time jobs, and bedrooms equipped with screen media—get much less sleep than teenagers of previous generations. Sleep-deprived adolescents display declines in executive function and both cognitive and emotional self-regulation. As a result, they are likely to achieve less well in school; suffer from anxiety, irritability, and depressed mood; and engage in high-risk behaviors. Later school start times ease but do not eliminate sleep loss

Decision Making

Think back, once again, to evidence indicating that adolescent changes in the brain's emotional/social network outpace development of the prefrontal cognitive-control network. Consequently, teenagers often perform less well than adults in decision making, where they must inhibit emotion and impulses in favor of thinking rationally. Good decision making involves (1) recognizing the range of possible response options, (2) identifying pros and cons of each alternative, (3) assessing the likelihood of various outcomes, (4) evaluating one's choice in terms of whether one's goals were met and, if not, (5) learning from the mistake and making a better future decision. When researchers modified a card game to trigger strong emotion by introducing immediate feedback about gains and losses after each choice, teenagers behaved more irrationally, taking far greater risks than adults in their twenties (Figner et al., 2009). In decision-making contexts, adolescents are far more enticed than adults are by the possibility of immediate reward (see page 302)—more willing to take risks and less likely to avoid potential losses (Christakou et al., 2013; Defoe et al., 2015). Nevertheless, teenagers are less effective than adults at decision making even under "cool," unemotional conditions (Huizenga, Crone, & Jansen, 2007). They less often carefully evaluate alternatives, instead falling back on well-learned intuitive judgments (Jacobs & Klaczynski, 2002). Consider a hypothetical problem requiring a choice, on the basis of two arguments, between taking a traditional lecture class and taking a computer-based class. One argument contains large-sample information: course evaluations from 150 students, 85 percent of whom liked the computer class. The other argument contains small-sample personal reports: complaints of two honor-roll students who both hated the computer class and enjoyed the traditional class (Klaczynski, 2001). Most adolescents, even those who knew that selecting the large-sample argument was "more intelligent," based their choice on the small-sample argument, which resembled the informal opinions they depend on in everyday life. Earlier we noted that processing skills governed by the prefrontal cognitive-control network, such as decision making, develop gradually. Like other aspects of cognitive development, decision making is affected by experience. As "first-timers" in many situations, adolescents do not have sufficient knowledge to consider pros and cons and predict likely outcomes. And after engaging in risky behavior without negative consequences, teenagers rate its benefits higher and its risks lower than peers who have not tried it (Halpern-Felsher et al., 2004). These faulty judgments increase the chances of continued risk taking. School and community interventions that teach effective decision-making skills can help adolescents apply their capacity for metacognition by reflecting on and monitoring the decision process (Bruine de Bruin, 2012). But because taking risks without experiencing harmful outcomes can heighten adolescents' sense of invulnerability, they need supervision and protection from high-risk experiences until their decision making improves.

biological, psychological, and social forces on adolescence

Today we know that biological, psychological, and social forces combine to influence adolescent development. Biological changes are universal—found in all primates and all cultures. These internal stresses and the social expectations accompanying them—that the young person give up childish ways, develop new interpersonal relationships, and take on greater responsibility—are likely to prompt moments of uncertainty, self-doubt, and disappointment in all teenagers. Adolescents' prior and current experiences affect their success in surmounting these challenges. At the same time, the length of adolescence and its demands and pressures vary substantially among cultures. Most tribal and village societies have only a brief intervening phase between childhood and full assumption of adult roles. In industrialized nations, young people face prolonged dependence on parents and postponement of sexual gratification while they prepare for a productive work life. As a result, adolescence is greatly extended. The more the social environment supports young people in achieving adult responsibilities, the better they adjust. For all the biological tensions and uncertainties about the future that teenagers feel, most negotiate this period successfully.

Do All Individuals Reach the Formal Operational Stage?

Try giving one or two of the formal operational tasks just described to your friends. How well do they do? Even well-educated adults often have difficulty (Kuhn, 2009; Markovits & Vachon, 1990). Individuals are most likely to think abstractly and systematically on tasks in which they have had extensive guidance and practice in using such reasoning (Kuhn, 2013). This conclusion is supported by evidence that taking college courses leads to improvements in formal reasoning related to course content (Lehman & Nisbett, 1990). Like concrete reasoning in children, formal operations do not emerge in all contexts at once but are specific to situation and task (Keating, 2004, 2012). Individuals in tribal and village societies rarely do well on tasks typically used to assess formal operational reasoning (Cole, 1990). Piaget acknowledged that without the opportunity to solve hypothetical problems, people in some societies might not display formal operations. Still, researchers ask, Does formal operational thought largely result from children's and adolescents' independent efforts to make sense of their world, as Piaget claimed? Or is it a culturally transmitted way of thinking that is specific to literate societies and taught in school? In an Israeli study of seventh to ninth graders, after controlling for participants' age, researchers found that years of schooling fully accounted for early adolescent gains in propositional thought (Artman, Cahan, & Avni-Babad, 2006). School tasks, the investigators speculated, provide crucial experiences in setting aside the "if ... then" logic of everyday conversations that is often used to convey intentions, promises, and threats ("If you don't do your chores, then you won't get your allowance") but that conflicts with the logic of academic reasoning. In school, then, adolescents encounter rich opportunities to realize their neurological potential to think more effectively.

How scientific reasoning develops

What factors support skill at coordinating theory with evidence? Greater working-memory capacity, permitting a theory and the effects of several variables to be compared at once, is vital. Adolescents also benefit from exposure to increasingly complex problems and to instruction that highlights critical features of scientific reasoning—for example, why a scientist's expectations in a particular situation are inconsistent with everyday beliefs and experiences (Chinn & Malhotra, 2002). This explains why scientific reasoning is strongly influenced by years of schooling, whether individuals grapple with traditional scientific tasks (like the sports-ball problem) or engage in informal reasoning—for example, justifying a theory about what causes children to fail in school (Amsel & Brock, 1996). Sophisticated metacognitive understanding is vital for scientific reasoning (Kuhn, 2011, 2013). When adolescents regularly pit theory against evidence over many weeks, they experiment with various strategies, reflect on and revise them, and become aware of the nature of logic. Then they apply their appreciation of logic to an increasingly wide variety of situations. The ability to think about theories, deliberately isolate and control variables, and inhibit an initial choice long enough to actively seek disconfirming evidence and weigh alternative possibilities is rarely present before adolescence (Kuhn, 2000; Kuhn et al., 2008). But adolescents and adults vary widely in scientific reasoning skills (Kuhn, 2011). Many continue to show a self-serving bias, applying logic more effectively to ideas they doubt than to ideas they favor. Reasoning scientifically requires the metacognitive capacity to evaluate one's objectivity—to be fair-minded rather than self-serving (Moshman, 2011). As we will see in Chapter 12, this flexible, open-minded approach is both a cognitive attainment and a personality trait—one that assists teenagers greatly in forming an identity and developing morally. Information-processing findings confirm that scientific reasoning does not result from an abrupt, stagewise change. Instead, it develops gradually out of many specific experiences that require children and adolescents to match theories against evidence and reflect on and evaluate their thinking.

Sexuality in adolescence

With the arrival of puberty, hormonal changes—in particular, the production of androgens in young people of both sexes—lead to an increase in sex drive. In response, adolescents become very concerned about managing sexuality in social relationships. Improved cognitive capacities involving perspective taking and self-reflection affect their efforts to do so. Yet like the eating behaviors we have just discussed, adolescent sexuality is heavily influenced by the young person's social context.

Trends in physical activity in adolescents

Yet physical activity among U.S. adolescents declines dramatically with age. When researchers followed a large, representative sample of U.S. youths from ages 9 to 17, daily free-time exercise steadily diminished, more so for girls than boys. And at every age, only a minority of participants engaged in regular exercise outside of school hours. In high school, just 55 percent of U.S. boys and 48 percent of girls receive any physical education, with just 30 percent of all students experiencing a daily physical education class

The role of physical attractiveness in adolescence

You will see evidence of our society's view of an attractive female as thin and long-legged and of a good-looking male as tall, broad-shouldered, and muscular. The female image is a girlish shape that favors the late developer. The male image fits the early-maturing boy. Consistent with these preferences, early-maturing European-American girls tend to report a less positive body image—conception of and attitude toward their physical appearance—than their on-time and late-maturing agemates. Compared with African-American and Hispanic girls, European-American girls are more likely to have internalized the cultural ideal of a thin female body. Although boys are less consistent, early, rapid maturers are more likely to be satisfied with their physical characteristics Body image is a strong predictor of young people's self-esteem. But the negative effects of pubertal timing on body image and—as we will see next—emotional adjustment are greatly amplified when accompanied by other stressors

Impact of School Transitions

school transitions can create adjustment problems. With each school change—from elementary to middle or junior high and then to high school—adolescents' grades decline (Benner, 2011; Ryan, Shim, & Makara, 2013). The drop is partly due to tighter academic standards, but school transitions are also associated with reductions in achievement test scores and attendance, which cannot be explained by tougher grading (Benner & Wang, 2014; Schwerdt & West, 2013). The transition to secondary school often means less personal attention, more whole-class instruction, and less chance to participate in classroom decision making. It is not surprising, then, that students often rate their middle and high school experiences less favorably than their elementary school experiences, stating that their teachers care less about them, grade less fairly, and stress competition more. Consequently, many young people feel less academically competent and decline in motivation (Barber & Olsen, 2004; De Wit et al., 2011; Otis, Grouzet, & Pelletier, 2005). Adolescents facing added strains—family disruption, poverty, low parent involvement, high parental conflict, or learned helplessness on academic tasks—are at greatest risk for self-esteem and academic difficulties (de Bruyn, 2005; De Wit et al., 2011; Seidman et al., 2003). Furthermore, the high school transition is especially challenging for African-American and Hispanic students who move to a new school with substantially fewer same-ethnicity peers (Benner & Graham, 2009). Under these conditions, minority adolescents report decreased feelings of belonging and school liking, and they show steeper declines in grades. Distressed youths whose school performance either remains low or drops sharply after school transition often show a persisting pattern of poor self-esteem, motivation, and achievement along with a rise in truancy and out-of-school problem behaviors. They often turn to similarly alienated peers for approval and support they lack in other spheres of life (Roeser, Eccles, & Freedman-Doan, 1999; Rubin et al., 2013). For these vulnerable youths, the transition to high school may initiate a downward spiral in school involvement that leads to failure and dropping out.`

adolescence

the transition between childhood and adulthood. In industrialized societies, the skills young people must master are so complex and the choices confronting them so diverse that adolescence is greatly extended. But around the world, the basic tasks of this period are much the same. Sabrina must accept her full-grown body, acquire adult ways of thinking, attain greater independence from her family, develop more mature ways of relating to peers of both sexes, and begin to construct an identity—a secure sense of who she is in terms of sexual, vocational, moral, ethnic, religious, and other life values and goals. Adolescence also brings with it vastly expanded powers of reasoning. Teenagers can grasp complex scientific and mathematical principles, grapple with social and political issues, and delve deeply into the meaning of a poem or story.